No abstract

Bacillus megaterium is a gram - positive rod-shaped endospore-forming bacteria. They are used as an effective soil modifier, having the ability to disperse phosphorus. In turn, phosphorus plays an important role in several physiological and biochemical processes of plants, such as photosynthesis, the conversion of sugar to starch, and the transfer of genetic traits. Based on the current state of research in the development of biofertilizers, it can be argued that the biocomposition of Bacillus megaterium bacteria will lead to an increase in the availability of a number of macronutrients for plants – the main elements of nutrition. This article presents the results of screening studies of previously created collection of bacterial strains of Bacillus megaterium from the Museum of the Department of microbiology, virology, epizootology and VSE of Ulyanovsk SAU. The developed scheme of isolation and identification of Bacillus megaterium bacteria is given. The species identity of 6 strains of B. megaterium was confirmed. The results of the research are compared with the characteristic phenotypic properties of the studied species described in "Bergey's Manual of Systematic Bacteriology" (2015). 210 soil samples were taken to isolate new strains of microorganisms. Initial identification allowed us to isolate 58 strains of bacteria of the genus Bacillus, 16 were assigned to Bacillus megaterium. The percentage of contamination of soil samples of this type of bacteria was 7.6 %. As the result of research, the collection of bacterial strains of studied microorganisms was expanded and their taxonomic affiliation was determined. The resulting collection will be the object of research at the following stages of work on the development of biocomposition based on bacteria to increase the coefficient of absorption of mineral components of fertilizers.

Soil is a vital and valuable natural resource that sustains life on earth. Appropriate soil functioning depends on the balance of its structure and composition, as well as physical, chemical and biological properties. Often, this balance is disturbed under the influence of various abiotic, biotic and anthropogenic factors. Therefore, soil restoration is of great importance in order to prevent possible adverse effects on living systems and to preserve the environment for future generations. Various studies confirmed the effectiveness of introduction of rhizobacteria to improve soil fertility, increase growth and productivity of agricultural crops. Bacillus subtilis is one of the most common rhizobacteria used in agriculture. Many B. subtilis strains are capable of fixing atmospheric nitrogen, solubilizing phosphorus and potassium, thereby contributing to an increase in the amount of macroelements necessary for plant nutrition in soil. The aim of this work was to search for genes responsible for synthesis of phytase, nitrogenase, and alkaline phosphatase enzymes in strains of bacteria of Bacillus subtilis species by real-time PCR. To determine the presence of genes encoding the synthesis of the desired enzymes in Bacillus subtilis, an in-silico analysis of the annotated genomes of this bacterial species presented in the NCBI information database was carried out. Then the selection of primers for screening the target spots was made. According to the results of the study, 10 out of 19 isolated Bacillus subtilis strains contained all three required DNA regions responsible for synthesis of phytase, nitrogenase, and alkaline phosphatase enzymes.

The soil microbial component plays a critical role in maintaining the soil functionality, performing several vital functions such as soil formation, decomposition of dead and decayed organic matter, circulation of macro and micro elements and transformation of toxic chemicals into non-toxic forms. Various Bacillus species, including B. megaterium, are known to fix atmospheric nitrogen. To ensure nitrogen fixation and diversity analysis of diazotrophs, the most widely used gene marker is nifH, which is responsible for synthesis of proteins of the nitrogenase complex. Various soil microorganisms, including B. megaterium, are endowed with the ability to solubilize phosphorus inaccessible form to accessible one and / or mineralize organic phosphorus to accessible phosphorus form. Phosphatases and phytases are two groups of enzymes that catalyze transformation of organic phosphates to inorganic ones. It was found that Bacillus megaterium exhibits acidic and alkaline phosphatase activity and produces phytases. The aim of this work was to determine by RT-PCR method the presence of genes responsible for enzyme synthesis of phytase, nitrogenase, and alkaline phosphatase in strains of previously isolated bacteria of Bacillus megaterium species. To specify the presence of genes encoding synthesis of the desired enzymes in Bacillus megaterium, an in-silico analysis of the annotated genomes of this bacterial species, presented in the NCBI information database, was carried out. Further on, the selection of primers for screening the target parts was made. According to the results of the study, 7 out of 16 isolated B. megaterium strains contained all three required DNA parts responsible for synthesis of phytase, nitrogenase, and alkaline phosphatase enzymes.